Democrats have long known that 2010 would be a difficult year politically, but the decision by embattled Sen. Christopher J. Dodd (Conn.) not to seek reelection, along with similar announcements by another longtime senator and a once-rising star among Western governors, brought home that reality with unexpected intensity Wednesday.

After two big elections, Democrats are due for a setback. The decisions by Dodd, Sen. Byron L. Dorgan (N.D.) and Colorado Gov. Bill Ritter speak to that calculus. For their own reasons, the three concluded that the outlook for their futures will not change dramatically by November. Collectively they sent a message that signals the nervousness of incumbents -- particularly Democratic incumbents -- in a year when voter dissatisfaction is palpable.

As the midterm election year opens, the euphoria among Democrats that accompanied President Obama's inauguration has disappeared in the face of a high unemployment rate and controversy over their efforts to pass comprehensive health-care legislation. Even the least pessimistic Democrats fear sizable losses in November. The question is how substantial. Democrats now face the evaporation of their 60-vote filibuster-proof majority in the Senate and losses in the House that a number of strategists across party lines conservatively estimate in the range of 20 to 25 seats.

Republicans also predict that by the end of this year, they will control the majority of the nation's governors.

In some Democratic circles, including at the White House, there is hope that by fall, the political landscape may look less forbidding. That hope is based on two assumptions: that the economic outlook will be brighter, and that health-care changes will prove more popular with the public after the legislation's expected passage than they have during the long congressional debate. Some Democrats also note that Republicans have done little to improve their popularity among voters.

"Do we have challenges? Of course. That comes with the terrain and the economic situation we find ourselves in and the history of midterm elections," said White House senior adviser David Axelrod. "But I think the economy's going to improve, and we've accomplished a lot this year. . . . We understand the challenge. But gloomy? No."

But Vin Weber, a former House member and longtime GOP strategist, said whatever doubts voters may have about Republicans "will matter less" in the midterms than they might in a presidential campaign. The onus, he said, will be on Democrats to show that they are not out of touch with the electorate.

"Democrats are still committed to an agenda that was forged at a time when they thought the country was at a very different place ideologically and had reason to believe that it was at a different place," he said.

Behind the decisions

Dodd's decision not to run again has been the least surprising of this week's announcements. He has had a productive year legislatively, but the past three years have brought political setbacks, from a presidential campaign that never got off the ground to controversy over a seeming sweetheart loan from Countrywide Financial to public antipathy toward the financial industry bailout that he, among others, championed. Few incumbents looked as threatened as Dodd.

Dorgan has had a long and successful run in the Senate but could see trouble ahead, particularly if popular Gov. John Hoeven (R) decided to challenge him. Dorgan has watched a succession of brutal Senate campaigns in neighboring South Dakota, one of which cost former Democratic leader Thomas A. Daschle his seat, and could probably imagine himself in the same kind of expensive, no-holds-barred battle this year.

Ritter said the toll that being governor has taken on his family was the reason he decided not to seek reelection. But he and his advisers have known for months that Colorado, after a series of elections in which Democrats won big, will be more hospitable to Republicans in 2010 than it has been in several cycles.

The GOP's internal war

Not that Republicans are without problems. Were it not for the news of the Democratic retirements, Tuesday might have received more attention as a day when the GOP's internal wars counted another victim, this time the party chairman in Florida, Jim Greer. Greer, an ally of Florida Gov. Charlie Crist (R), got caught up in the nasty Senate primary contest between Crist and former state House speaker Marco Rubio, a darling of conservatives.

Florida's GOP primary is, writ large, a replay of what happened in New York's 23rd Congressional District in November, when Sarah Palin and other conservatives spurned the Republican nominee in a House special election and sided with the Conservative Party candidate. The upshot was that Democrats won a seat that the GOP had held for more than a century.

Democrats also point out that half a dozen Republican senators and about a dozen Republican House members have announced their retirements. But many of those decisions came at a time when the GOP's fortunes were far worse than they are today.

Lessons from 2006

The midterm elections are likely to be a referendum on the party in power, even if the public is not wild about the alternative. Democrats should remember the lesson of the 2006 elections, when anger at President George W. Bush and the GOP proved a more powerful motivator for voters than reservations they had about the Democrats' capacity to govern.

Much can change by November, especially with the economy. But at this point, Republicans have a more motivated constituency and a greater chance of winning independent voters than in the past two elections, as their gubernatorial victories in Virginia and New Jersey two months ago showed. But unlike in 1994, when Republicans caught many Democrats off guard and captured the House and the Senate, Democratic incumbents have plenty of time to prepare.

Democratic strategists believe that Dodd's decision not to run improves the party's chances of holding the Connecticut seat. Republicans are confident that Dorgan's departure gives them a boost in North Dakota. Colorado political analysts say Ritter's decision sets the stage for confusion and competition among possible Democratic contenders, including Interior Secretary Ken Salazar, for the gubernatorial nomination, a prelude to what will be a challenge to hold his seat.

Two months ago, Democrats sought to portray losses in Virginia and New Jersey as driven by individual circumstances, not the start of a national trend. But there is no question that those elections have had a significant effect on the thinking of all Democratic incumbents and potential Republican challengers as they weigh decisions about the coming year.